The present invention relates to a false twist texturing apparatus for false twist texturing a plurality of synthetic yarns, of the general type disclosed in EP 0 641 877 and corresponding U.S. Pat. No. 5,644,908.
Such false twist texturing machines comprise a plurality of processing stations, which are arranged in side by side relationship along the longitudinal side of the machine. Each of the processing stations includes a plurality of feed roll systems as well as a primary heater, a cooling device, a false twist unit, a secondary heater, and a takeup device.
Basically, a difference is made between two types of false twist texturing machines. In a first type, on which the invention is based, the packages wound in the takeup device are automatically doffed and automatically removed by doffers. To this end, the false twist texturing machine as disclosed in the above patents includes a separate doffing aisle, which permits removing the fully wound packages. The doffing aisle extends along one side of a takeup module, which accommodates the takeup devices. For operating the processing units in the false twist texturing machine, a separate servicing aisle is provided, which extends along the opposite side of the takeup module and between the takeup module and a processing module.
In a second type of false twist texturing machine, the packages wound in the takeup device are manually doffed. False twist texturing machines of this type as disclosed, for example, in EP 0 659 913 comprise a single servicing aisle for purposes of enabling both the package doff and the operation of the processing units by one operator. For this reason, false twist texturing machines of this type are totally unsuited for enabling an automatic removal of the wound packages.
When both a servicing aisle and a separate doffing aisle are employed, the processing units of the first type of false twist texturing machines are arranged in such a manner that the yarn traverses the servicing aisle several times, which leads to a plurality of yarn deflections.
It is therefore an object of the invention to further develop the false twist texturing machine of the first type in such a manner that a shortest possible yarn path results with the least possible yarn deflections.
In accordance with the invention, the above and other objects and advantages are achieved by positioning the processing module and the takeup module so that they are joined to form a frame section arranged between the servicing aisle and the doffing aisle, and so that the passage of the yarn from the processing module to the takeup module is formed by a generally horizontally oriented secondary heater. Further, the yarn advances in the frame section between the false twist unit and the takeup device along a generally U-shaped path, with the secondary heater being located at the base of the u-shaped path.
The invention distinguishes itself by a very compact construction and by a very stable threadline. The passage of the yarn between the processing module and the takeup module is used as a set zone, in which the heat treatment of the yarn occurs by means of the secondary heater. As a result, additional yarn deflections can advantageously be avoided.
A preferred further development of the invention has the advantage that it prevents a crossing yarn path in the false twist texturing machine. To this end, the processing module is associated on the opposite side of the servicing aisle with a feed module for accommodating a withdrawal roll system. The passage of the yarn from the feed module to the processing module is formed by the primary heater and the cooling device, which are arranged above the servicing aisle in such a manner that the yarn advances from the withdrawal roll system to the false twist unit along a substantially inverted V-shaped path. With the compact construction of the modules, it is possible to realize a very long false twist zone for tempering and subsequently cooling the yarn.
During the heat aftertreatment in the set zone, the yarn advances under very little tension, so as to enable a shrinkage treatment of the yarn in the set zone. However, this makes it necessary that the guidance of the yarn ensure a uniform tempering of the yarn within the secondary heater. In this connection, it has been found that the use of a contact heater is possible, in particular as a result of a further development of the invention wherein the secondary heater is placed on the underside of the frame section, so that after passing through the processing module, the yarn can be transferred directly to the takeup module.
With the use of a contact heater, the secondary heater is arranged with an inclination, preferably in an angular range from about 5xc2x0 to about 45xc2x0.
To avoid additional yarn guide elements, the processing module mounts one of the feed roll systems between the false twist unit and the secondary heater in such a manner that the yarn outlet of the feed roll system and the yarn inlet on the secondary heater are aligned with each other in facing relationship.
Similarly, a further feed roll system is arranged on the takeup module below the takeup device in such a manner that the yarn inlet of the feed roll system and the yarn outlet of the secondary heater are aligned in facing relationship.
In this arrangement, the yarn deflection is realized in an advantageous manner by a feed roll system, which is formed by a godet that is looped by the yarn several times, and with a yarn guide roll associated therewith. In this connection, the yarn inlet on the secondary heater and the yarn outlet on the secondary heater are each arranged in tangential relationship with the godets of the feed roll systems. There are no yarn guide elements between the feed roll systems and the secondary heater.
To ensure an easy operability despite the high integration of the modules, in particular when threading the yarn, a further development of the invention provides a heating channel in the secondary heater which connects to an injector, which is designed to permit an automatic threadup of the yarn through the heating channel. For a further automation, it is also proposed to associate a further injector of a threading device with the yarn outlet of the secondary heater, with the threading device guiding the yarn as far as the takeup device.
To enable in the false twist zone an unimpeded return of the false twist into the primary heater, an advantageous further development of the invention provides that the primary heater and the cooling device are arranged in a generally linear arrangement above the servicing aisle. With that, it is possible to realize intensive crimps in the yarn.
In cases which do not require a heat aftertreatment of the yarn, it would be possible, for purposes of maintaining the yarn path, to replace the secondary heater with a guide tube of the threading device.